干姜以母姜去皮依法造之，色黄白而气味辛温，体质坚结，为温中土之专药，理中汤用
之，正如其本量。其性散不如守，故能由胃达肺而无泄邪、出汗、止呕、行水之长。炮黑亦
入肾，而无附子乌头之大力。凡仲圣方用干姜，总不外乎温中，其故可玩索而得也。
通脉四逆汤，即四逆汤倍加干姜，脉不出又加人参，似干姜与人参皆能通脉，功不止于
温中矣。不知壅遏营气令无所避是谓脉。营出中焦，中焦泌糟粕蒸津液。下利则中焦失职，
焉得不脉微欲绝。欲脉之出，自非温中止利不可。必利止而脉不出，则其故不在中焦而在主
脉之心。然后加以补心通血脉之人参，非干姜不通脉，非通脉不关温中也。
肺痿有得之燥热，有得之虚冷。虚冷之痿，以甘草干姜汤治之，谓干姜温肺，是固然矣。
岂知金生于土，土不温者上必虚，上虚则不能制下，其头眩多涎唾者上虚也，遗尿小便数者
下虚也，而皆由于中之不温也。然则干姜非不温肺，惟不越脾以温肺耳。
或曰∶伤寒误攻其表，服甘草干姜汤，便厥愈足温，则干姜不独温中，且更温下矣。曰∶
干姜讵能温下，惟炮之而后能耳。然虽炮用，其温下之气犹不毕贯，更进以芍药甘草汤，而
不贯者始贯，脚始伸而不挛，此其旨甚微，非一二言所得罄焉。夫脉浮、自汗出、心烦、微
恶寒者，邪在表也。小便数、脚挛急者，太阳寒邪袭入少阴。或先有伏寒，因而致剧也。医
以桂枝汤但攻其表，内有芍药酸寒入里，反增下寒，于是得之即厥。始而心烦、微恶寒者，
兹更肾寒而躁，阴中之阳，又随桂枝外发之势而欲越，故咽干与吐逆并作。此时自汗之表邪，
已受治于桂枝，但以炮姜温下，炙草和中，未有不阳复而自愈者。而足温而挛急如故，宁非
温下之力犹有歉哉。然非真阳亏损，附子可无用也。前为芍药所误者，今乃以芍药伸脚矣。
芍药何以能然，正惟炮姜以芍药抑之而后能尽复其阳也。肺痿何以不更进芍药甘草汤，以但
遗尿小便数而脚不挛急，且炮姜并欲其温肺也。则谓干姜若不炮，温中而不温下可也。
诸四逆汤治少阴病而用干姜，似干姜亦所以温下，不知少阴寒甚，必上侮及脾，用附子
以斩将搴旗，犹当佐干姜以储粮坚壁。理中丸干姜用三两，以温中固干姜责也。四逆汤干姜
用两半，以温少阴有附子任之，干姜为附子后殿也。更观肾着汤病属下焦，而方中有脾药无
肾药，益以见温下之必当温中矣。
四逆汤重在厥逆，下利是兼证，有干姜不必有葱白。白通汤治少阴下利，是正病无兼证，
不升其阴气以与阳通，则利终不止，故君葱白而协以姜附。桃花汤干姜只一两，则少而又少
矣，且无附子无葱白，何以为解？曰∶此非少阴纯寒之证也，以石脂粳米固下和中，略施干
姜，使就温化，不利其便不清其血而但止其利，法之至超至妙者也。若赤石脂禹余粮汤，利
在下焦而治以中焦药不应，则桃花汤之有干姜，不尚于中宫有涉哉。
干姜温脾而上及肺，以治肺咳而下连脾，正为相当。如小青龙汤以干姜治寒咳而用至三
两，微利亦不去干姜是也。
本经干姜主止血，仁斋直指云∶血遇热则宣行，故止血多用凉药，然亦有气虚挟寒，阴
阳不相为守，营气虚散，血亦错行者，窃谓血统于脾，有出中焦，营气虚散之证，非温中土
不可。金匮胶艾汤，无干姜而千金方有之。黄土汤虽无干姜，而灶中黄土，其用与干姜无二。
干姜温中，自有止血之理。虽然不能无佐使之品也。大抵吐血而至不止，则在上者宜抑之，
漏血而至不止，则在下者宜举之。凡用柏叶阿胶之类为佐使者，所以导血归经。用黄芩童便
之类为佐使者，所以养阴和阳，非能抑之能举之也。独柏叶汤之用马通，有匪夷所思者。马
之气最盛者，能使血随汗出，而一身之物，非性寒即有毒，惟通温而无毒，虽秽滓乎，固化
气化血行脉络之余而性能下行者也。此佐干姜，以抑为止者也。妇人陷经漏下黑不解胶姜汤
主之，黑多由于热，而虚寒之人，血出络而凝，渐渐变紫变黑，亦未尝无之，胶姜汤之姜，
其为干姜无疑。乃陈修园以此二味治是证，一再用之不瘥，后易干姜为生姜，并加阿胶大枣，
煎服立止，谓生姜散寒升气，合陷者举之之义，此与马通一抑一举，可为对待。然先服之干
姜未必无功，或如仲圣法以生干并用，当收效尤捷耳。
仲圣方干姜黄连并用之证，必兼有呕。呕属少阳，故方中必有黄芩人参少阳专门之药。
盖少阳为三阳之枢，以黄连降胃阳，干姜升脾阴，脾升胃降，少阳乃得转枢，此少阳无往来
寒热之治法，治在此而效见于彼者也。
干姜是由母姜去皮后按照特定方法加工制成的，其颜色呈黄白色，气味辛温，质地坚实紧密，是温暖中焦脾胃的专用药物。理中汤中使用它，正是符合其本来的药性剂量。干姜的药性偏于发散而非固守，因此它能从胃气上行至肺气，具有驱散邪气、发汗、止呕和行水的作用。炮制变黑后的干姜也能入肾经，但力量不如附子和乌头那样猛烈。凡是张仲景的方剂中使用干姜，总离不开温暖中焦这一作用，其中的道理是可以深入探究而得到的。
通脉四逆汤，就是在四逆汤的基础上加倍使用干姜，如果脉搏仍摸不到，再加用人参。这似乎表明干姜与人参都能通达血脉，功效不仅仅局限于温暖中焦。然而，所谓“壅遏营气令无所避是谓脉”，意思是营气运行受阻，无处躲避而充盈于脉道才称为脉。营气产生于中焦，中焦负责分离糟粕、蒸化津液。当下利时，中焦功能失职，脉象怎么会不微弱得几乎要断绝呢？想要让脉象恢复出现，自然非用温暖中焦并停止下利不可。只有当腹泻停止后脉搏仍然不出，那么原因就不在中焦，而在于主宰血脉的心脏了。这时再加入补益心脏、通达血脉的人参，并不是说干姜不能通达血脉，也不是说通达血脉与温暖中焦没有关系。
肺痿病有的因燥热引起，有的因虚冷引起。对于虚冷引起的肺痿，用甘草干姜汤治疗，说干姜能温暖肺部，这固然正确。但岂不知金（肺）生于土（脾），土如果不温暖，上部（肺）必然虚弱；上部虚弱则不能制约下部，所以头晕、多涎唾是因为上部虚弱，遗尿、小便频数是因为下部虚弱，而这些都源于中焦的不温暖。既然如此，干姜并非不温暖肺部，只是不越过脾脏去直接温暖肺部罢了。
有人问：伤寒误用攻下法治疗表证，服用甘草干姜汤后，手足厥冷痊愈、足部变暖，这说明干姜不仅温暖中焦，还温暖下焦。回答说：干姜难道能温暖下焦吗？只有经过炮制后才能做到。然而即使炮制使用，其温暖下焦的气力还不能完全贯通，再进服芍药甘草汤，那些未能贯通的地方才开始贯通，脚才能伸直而不痉挛，其中的旨意非常微妙，不是一两句话能说尽的。脉浮、自汗出、心烦、轻微恶寒，这是邪气在体表。小便频数、脚部拘挛急迫，这是太阳寒邪侵袭进入少阴经。或者原本就有潜伏的寒邪，因而导致病情加剧。医生只用桂枝汤攻治表邪，方中的芍药酸寒入里，反而增加了下部的寒邪，于是服药后立即出现手足厥冷。起初的心烦、轻微恶寒，现在更变为肾寒而躁动，阴中之阳，又随着桂枝向外发散的势头想要外越，所以咽干与呕吐并作。此时体表的自汗邪气，已经受到桂枝汤的治疗，但如果仅用炮姜温暖下焦，炙甘草调和中部，没有阳气回复而不能自愈的。然而足部虽然变暖，但拘挛急迫依旧，这难道不是温暖下焦的力量还有欠缺吗？但这并非真阳亏损，所以附子可以不用。之前被芍药所误导的情况，现在却靠芍药来舒展脚部。芍药为什么能起到这个作用？正是因为炮姜借助芍药的抑制作用，然后才能完全恢复阳气。肺痿为什么不继续进服芍药甘草汤？因为仅仅有遗尿和小便频数，而没有脚部拘挛急迫，而且炮姜同时也想用它来温暖肺部。所以说，如果干姜不经过炮制，只能温暖中焦而不能温暖下焦，这是可以的。
各种四逆汤治疗少阴病时使用干姜，看似干姜也是用来温暖下焦的，却不知道少阴寒邪严重，必定会上犯侵犯脾脏，使用附子如同斩将夺旗般强力破寒，还应当辅佐干姜以储备粮草、巩固壁垒。理中丸中干姜用量为三两，是为了温暖中焦，责任主要在干姜。四逆汤中干姜用量为一两半，是因为温暖少阴有附子担当主要任务，干姜则是作为附子的后卫支援。再看肾着汤，病属下焦，但方中有治脾的药物而没有治肾的药物，更加证明了温暖下焦必须通过温暖中焦来实现。
四逆汤的重点在于手足厥逆，下利是兼夹症状，有干姜不一定需要有葱白。白通汤治疗少阴病下利，这是主病而没有兼夹症状，如果不升举阴气与阳气相通，下利最终不会停止，所以以葱白为君药，配合姜、附。桃花汤中干姜只有一两，用量很少，而且没有附子和葱白，这是什么解释呢？回答说：这不是少阴纯寒的证候，而是用赤石脂、粳米固涩下部、调和中部，稍微施用干姜，使其能够温化，不通过利尿来清血，而是单纯止住下利，这是极其高超巧妙的治法。如果是赤石脂禹余粮汤，病在下焦却用中焦药物治疗无效，那么桃花汤中使用干姜，不更是与中宫（脾胃）有关联吗？
干姜温暖脾脏而上达肺部，用于治疗肺咳；同时向下连接脾脏，正为相当。如小青龙汤用干姜治疗寒咳，用量高达三两，即使有轻微下利也不去掉干姜，就是这个道理。
《神农本草经》记载干姜主治止血，仁斋直指说：血液遇到热就会宣散流行，所以止血多用凉药。然而也有气虚挟带寒邪，阴阳不能相互守持，营气虚弱散乱，血液也会错乱运行的情况。我认为血统属于脾，出自中焦，对于营气虚弱散乱的证候，非温暖中焦脾胃不可。《金匮要略》中的胶艾汤没有干姜，但《千金方》中有。黄土汤虽然没有干姜，但灶心黄土的作用与干姜没有二致。干姜温暖中焦，自有止血的道理。虽然不能没有佐使药物。大体上吐血不止，在上部的宜用抑制的方法；漏血不止，在下部的宜用升举的方法。凡是使用柏叶、阿胶等作为佐使的，是用来引导血液回归经脉。使用黄芩、童便等作为佐使的，是用来滋养阴液、调和阴阳，并不能起到抑制或升举的作用。唯独柏叶汤中使用马通（马粪汁），有匪夷所思之处。马的气最旺盛，能使血液随汗排出，而在所有动物之物中，不是性寒就是有毒，只有马通温热而无毒，虽然是秽浊之物，但固化气化后，血行脉络之余，其性能下行。这是佐助干姜，以抑制出血为目的。妇人陷经漏下黑色不解，用胶姜汤主治。黑色多由于热，但虚寒之人，血液流出络脉而凝结，渐渐变成紫色、黑色，也未尝没有这种情况，胶姜汤中的姜，无疑是干姜。但是陈修园用这两味药治疗此证，多次使用都不见效，后来将干姜改为生姜，并加入阿胶、大枣，煎服后立即止血，他说生姜能散寒升气，符合陷者举之的意义，这与马通的“一抑一举”，形成了对照。然而先前服用的干姜未必没有功劳，或许像张仲景的方法那样生干姜并用，应当收效更快。
张仲景方剂中干姜与黄连并用的证候，一定兼有呕吐。呕吐属于少阳病，所以方中必有黄芩、人参这些专门治疗少阳病的药物。大概因为少阳是三阳的枢纽，用黄连降胃阳，用干姜升脾阴，脾升胃降，少阳才能转枢运转，这是少阳病没有往来寒热时的治法，治疗在此处而疗效体现在别处。
Gan Jiang (Dried Ginger) is processed from the mother ginger root by peeling it and following specific methods. Its color is yellowish-white, its aroma and taste are pungent and warm, and its texture is firm and compact. It is a specialized medicine for warming the middle jiao (middle energizer, primarily referring to the Spleen and Stomach). In Lizhong Tang (Regulate the Middle Decoction), it is used precisely according to its fundamental dosage and nature. Its property is more dispersing than retaining, thus enabling it to move from the Stomach to the Lungs, possessing the functions of dispelling pathogenic factors, inducing sweating, stopping vomiting, and promoting water metabolism. When stir-fried until black, it also enters the Kidney meridian, but lacks the potent strength of Fu Zi (Aconite Root) and Wu Tou (Henbane Fruit). Whenever Zhang Zhongjing's formulas use Gan Jiang, it invariably pertains to warming the middle jiao; the rationale behind this can be understood through careful study.
Tongmai Sini Tang (Pulse-Reviving Four Reversal Decoction) is essentially Sini Tang (Four Reversal Decoction) with doubled amounts of Gan Jiang. If the pulse remains imperceptible, Ren Shen (Ginseng Root) is added. This might suggest that both Gan Jiang and Ren Shen can unblock the vessels, implying their efficacy extends beyond merely warming the middle jiao. However, "obstructing Ying Qi (Nutritive Qi) so that it has nowhere to avoid is called Mai (Vessels)." Ying Qi originates in the middle jiao, which separates waste products and steams fluids. When diarrhea occurs, the middle jiao fails in its duties, how could the pulse not become faint and nearly imperceptible? To restore the pulse, one must necessarily warm the middle jiao and stop the diarrhea. Only if the diarrhea stops yet the pulse remains absent should one look for causes outside the middle jiao, specifically in the Heart, which governs the blood vessels. Then, adding Ren Shen to tonify the Heart and unblock the vessels does not mean Gan Jiang cannot unblock the vessels, nor does it mean that unblocking vessels is unrelated to warming the middle jiao.
Fei Wei (Lung Withering) may result from dryness-heat or deficiency-cold. For deficiency-cold type Fei Wei, Gancao Ganjiang Tang (Licorice and Dried Ginger Decoction) is used. Saying that Gan Jiang warms the Lungs is indeed correct. But does one not know that Metal (Lungs) is born from Earth (Spleen)? If the Earth is not warm, the upper part (Lungs) will inevitably be deficient. Upper deficiency leads to an inability to control the lower part; thus, dizziness and excessive saliva indicate upper deficiency, while enuresis and frequent urination indicate lower deficiency. All these stem from the lack of warmth in the middle. Therefore, Gan Jiang does warm the Lungs, but it does so by warming the Spleen first rather than bypassing it.
One might ask: In cold damage (Shanghan), if the exterior was mistakenly attacked, and after taking Gancao Ganjiang Tang, the extremities recover warmth, does this not prove that Gan Jiang warms not only the middle but also the lower jiao? The response is: Can Gan Jiang warm the lower jiao directly? Only after processing (pao zhi) can it do so. However, even when processed, its warming qi may not fully penetrate. Administering Shaoyao Gancao Tang (Peony and Licorice Decoction) next allows the penetration to complete, enabling the legs to extend without cramping. The subtlety here is profound and cannot be fully explained in a few words. Floating pulse, spontaneous sweating, restlessness, and slight aversion to cold indicate pathogens in the exterior. Frequent urination and leg cramps indicate Taiyang cold pathogens invading the Shaoyin (Lesser Yin) channel. There may have been latent cold previously, exacerbating the condition. If a physician uses Guizhi Tang (Cinnamon Twig Decoction) solely to attack the exterior, the Sour-Cold nature of Shaoyao (Peony Root) entering the interior increases lower cold, leading immediately to Jue Ni (Reversal Cold/Extremity Cold). The initial restlessness and slight aversion to cold worsen into Kidney cold and agitation. The Yang within Yin, following the outward-expanding force of Guizhi, attempts to escape, causing dry throat and vomiting. At this point, the exterior pathogen causing sweating has been treated by Guizhi Tang. Using Pao Jiang (Processed Ginger) to warm the lower and Zhi Gan Cao (Honey-fried Licorice Root) to harmonize the middle ensures Yang recovery and self-healing. Yet, if the feet warm but cramps persist, is it not because the power to warm the lower jiao is insufficient? However, this is not due to a loss of True Yang, so Fu Zi (Prepared Aconite Root) is unnecessary. Previously misled by Shaoyao, now Shaoyao helps extend the legs. Why? Precisely because Pao Jiang, restrained by Shaoyao, allows Yang to fully recover. Why not continue with Shaoyao Gancao Tang for Fei Wei? Because there is only enuresis and frequent urination, without leg cramps, and Pao Jiang is also intended to warm the Lungs. Thus, if Gan Jiang is not processed, it warms the middle but not the lower jiao.
In various Sini Tang variants treating Shaoyin disease with Gan Jiang, it seems Gan Jiang warms the lower jiao. However, severe Shaoyin cold often insults the Spleen upwards. Using Fu Zi is like cutting down generals and capturing flags (a powerful attack), requiring Gan Jiang as support to store provisions and fortify defenses. In Lizhong Wan (Regulate the Middle Pill), Gan Jiang is used in 3 liang to warm the middle, bearing primary responsibility. In Sini Tang, Gan Jiang is used in 1.5 liang because Fu Zi takes charge of warming Shaoyin, with Gan Jiang acting as rear guard. Observing Shenzhuo Tang (Kidney-Dampness Decoction), where the disease is in the lower jiao but the formula contains Spleen herbs rather than Kidney herbs, further proves that warming the lower jiao necessitates warming the middle jiao.
Sini Tang focuses on Jue Ni (extremity reversal), with Xi Li (diarrhea) as a concurrent symptom; thus, Gan Jiang is present without necessarily needing Cong Bai (Scallion White). Baitong Tang (White Scallion Decoction) treats Shaoyin Xi Li as the primary disease without concurrent symptoms. Without raising Yin Qi to connect with Yang, diarrhea will not cease; hence, Cong Bai is the sovereign herb, assisted by Jiang (Ginger) and Fu Zi. In Taohua Tang (Peach Blossom Decoction), Gan Jiang is used in only 1 liang, a very small amount, and without Fu Zi or Cong Bai. How is this explained? This is not a pure cold syndrome of Shaoyin. Shi Li (Halloysitum Rubrum) and Jing Mi (Rice Grain) secure the lower and harmonize the middle. A slight application of Gan Jiang facilitates warming transformation. It stops diarrhea not by diuresis or clearing blood, but purely by arresting the flow, representing a highly sophisticated method. If Chishi Zhi Yuyuliang Tang (Red Halloysite and Hematite Decoction) fails because it treats lower jiao pathology with middle jiao herbs, then the presence of Gan Jiang in Taohua Tang clearly relates to the central palace (Spleen/Stomach).
Gan Jiang warms the Spleen and reaches the Lungs to treat Lung cough, while connecting downward to the Spleen, fitting appropriately. For example, in Xiao Qinglong Tang (Minor Blue Dragon Decoction), Gan Jiang is used in 3 liang to treat cold cough, and even with mild diarrhea, Gan Jiang is retained.
The Ben Jing (Divine Farmer's Materia Medica) states Gan Jiang stops bleeding. Ren Zhi Zhi Zhi says blood flows freely when heated, so hemostatics usually use cooling herbs. However, in cases of Qi deficiency with cold, where Yin and Yang fail to maintain each other, and Ying Qi is weak and scattered, blood may also circulate erratically. I believe blood belongs to the Spleen and emerges from the middle jiao. For syndromes of weak and scattered Ying Qi, warming the middle jiao is essential. Jiao Ai Tang (Colla Corii Asini and Mugwort Leaf Decoction) in Jin Gui Yao Lue lacks Gan Jiang, but Qian Jin Fang includes it. Huangtu Tang (Yellow Earth Decoction) lacks Gan Jiang, but Zaozhong Huangtu (Stove-heart Yellow Earth) serves a similar function. Gan Jiang warms the middle, inherently possessing hemostatic properties, though auxiliaries are needed. Generally, for persistent epistaxis/hematemesis (upper), suppression is appropriate; for persistent metrorrhagia/menorrhagia (lower), lifting is appropriate. Herbs like Bai Ye (Moss) and E Jiao (Donkey-hide Gelatin) guide blood back to the vessels. Huang Qin (Scutellaria Root) and Tong Bian (Child's Urine) nourish Yin and harmonize Yang, neither suppressing nor lifting. The use of Ma Tong (Horse Dung Juice) in Bai Ye Tang is extraordinary. Horse Qi is vigorous, causing blood to exit via sweat. Among animal substances, most are cold or toxic; only Ma Tong is warm and non-toxic. Though filthy, upon transformation, it aids blood circulation in the vessels and directs flow downward. Assisting Gan Jiang, it acts to suppress bleeding. For women with Xian Jing (Sunken Menses) and black leukorrhea/metrorrhagia not resolving, Jiao Jiang Tang (Colla and Ginger Decoction) is indicated. Black discharge usually indicates heat, but in deficiency-cold, blood coagulating in collaterals can turn purple/black. The Jiang in Jiao Jiang Tang is undoubtedly Gan Jiang. Chen Xiuyuan used these two herbs repeatedly without success, later replacing Gan Jiang with Sheng Jiang (Fresh Ginger) and adding E Jiao and Da Zao (Jujube), resulting in immediate cessation. He stated Sheng Jiang disperses cold and raises Qi, aligning with the principle of lifting sunken conditions, contrasting with Ma Tong's suppression. However, prior Gan Jiang usage likely had merit; perhaps using both Sheng and Gan Jiang together, as per Zhang Zhongjing's method, would yield faster results.
In Zhang Zhongjing's formulas where Gan Jiang and Huang Lian (Coptis Rhizome) are combined, vomiting is always present. Vomiting belongs to Shaoyang (Lesser Yang); thus, the formula must contain Huang Qin (Scutellaria Root) and Ren Shen, specific Shaoyang herbs. Shaoyang is the pivot of the three Yang channels. Huang Lian descends Stomach Yang, while Gan Jiang ascends Spleen Yin. With Spleen ascending and Stomach descending, the Shaoyang pivot turns. This is the treatment for Shaoyang disorders without alternating chills and fever, where the treatment targets one aspect but yields effects in another.